In dealing with communications systems, field intensities measured at an antenna are given in microvolts per meter (pV/m) . For high power televisions or AM and FM broadcast stations, the field intensity beyond a mile, but within 20 or 30 miles, may normally be in the millivolts per meter (mV/m) range. For the average TV owner, the field intensity measured at the home antenna would most likely be in the microvolt per meter range. This comparison will help to put the amount of energy beyond the rectenna site, due to sidelobe structure, in proper perspective. Referring back to Fig. 4.3., the right-hand scale has two number values. One is power density in milliwatts per square centimeter (mW/cm^) and the other is field intensity in volts per meter. Note that the field intensity beyond 50 km from the center of the rectenna site would still be 1 V/m at 2.45 GHz frequency. This intensity represents a sizable input to communication systems operating within 100 km of the rectenna site. Added to the electromagnetic field, due to sidelobes, is the power scattered from the main beam from media effects. Assessments have been made at five sites surrounding the rectenna site in the Mojave. These sites represent relatively large deployments of high- priority military operations. Those sites and their distances from the rectenna are given in Table 4.1. Propagation mechanisms for SPS energy include loss, and beam scattering and multipath components. • Sandstorms, • Rain, • Melting hail, • Atmospheric layers (multipath), • Atmospheric aerosols, and • Turbulence. SPS - China Lake Airstrip 64 km SPS - Downtown Barstow 51 km SPS - Edwards AFB Airstrip 43 km SPS - Restricted Area R 2524 53 km SPS - George AFB Airstrip 61 km Table 4.1. Selected Site Distances from Mojave Rectenna
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